// Incremental parsing engine implementation
use crate::{
    CodeChange, GraphUpdateResult, IncrementalEngine, NodeDifference, NodeId, Parser, Result,
    SyntaxTree, LanguageAdapter,
};
use async_trait::async_trait;
use std::collections::HashMap;
use std::sync::Arc;
use tokio::sync::RwLock;
use dashmap::DashMap;
use tracing::{debug, info};

/// Core incremental parsing engine with enhanced performance
pub struct IncrementalParseEngine {
    parsers: Arc<RwLock<HashMap<String, Box<dyn Parser>>>>,
    adapters: Arc<RwLock<HashMap<String, Box<dyn LanguageAdapter>>>>,
    change_detector: ChangeDetector,
    /// Cache for parsed syntax trees to enable incremental updates
    tree_cache: Arc<DashMap<String, CachedSyntaxTree>>,
    /// Cache for node differences to avoid recomputation
    diff_cache: Arc<DashMap<String, NodeDifference>>,
    /// Performance metrics
    metrics: Arc<DashMap<String, PerformanceMetrics>>,
    /// Configuration for the engine
    config: IncrementalEngineConfig,
}

/// Cached syntax tree with metadata
#[derive(Clone)]
struct CachedSyntaxTree {
    /// The actual syntax tree
    tree: Arc<dyn SyntaxTree>,
    /// Hash of the source content
    content_hash: String,
    /// Timestamp when cached
    cached_at: std::time::SystemTime,
    /// Number of times this tree has been accessed
    access_count: u64,
    /// Size in bytes (estimated)
    size_bytes: u64,
}

/// Performance metrics for the incremental engine
#[derive(Debug, Clone, Default)]
pub struct PerformanceMetrics {
    /// Total number of updates processed
    pub total_updates: u64,
    /// Average update time in milliseconds
    pub avg_update_time_ms: f64,
    /// Cache hit rate (0.0 to 1.0)
    pub cache_hit_rate: f64,
    /// Memory usage in bytes
    pub memory_usage_bytes: u64,
    /// Number of nodes processed
    pub nodes_processed: u64,
}

/// Configuration for the incremental engine
#[derive(Debug, Clone)]
pub struct IncrementalEngineConfig {
    /// Maximum cache size in bytes
    pub max_cache_size_bytes: u64,
    /// Maximum age for cached trees in seconds
    pub max_cache_age_seconds: u64,
    /// Enable parallel processing of node differences
    pub enable_parallel_processing: bool,
    /// Maximum number of concurrent workers
    pub max_concurrent_workers: usize,
    /// Enable aggressive caching
    pub enable_aggressive_caching: bool,
    /// Memory cleanup threshold
    pub memory_cleanup_threshold: u64,
}

impl Default for IncrementalEngineConfig {
    fn default() -> Self {
        Self {
            max_cache_size_bytes: 256 * 1024 * 1024, // 256MB
            max_cache_age_seconds: 3600, // 1 hour
            enable_parallel_processing: true,
            max_concurrent_workers: num_cpus::get().max(4),
            enable_aggressive_caching: true,
            memory_cleanup_threshold: 512 * 1024 * 1024, // 512MB
        }
    }
}

impl IncrementalParseEngine {
    pub fn new() -> Self {
        Self::with_config(IncrementalEngineConfig::default())
    }

    pub fn with_config(config: IncrementalEngineConfig) -> Self {
        Self {
            parsers: Arc::new(RwLock::new(HashMap::new())),
            adapters: Arc::new(RwLock::new(HashMap::new())),
            change_detector: ChangeDetector::new(),
            tree_cache: Arc::new(DashMap::new()),
            diff_cache: Arc::new(DashMap::new()),
            metrics: Arc::new(DashMap::new()),
            config,
        }
    }

    pub async fn register_adapter(&self, language: String, adapter: Box<dyn LanguageAdapter>) -> Result<()> {
        let mut adapters = self.adapters.write().await;
        adapters.insert(language, adapter);
        Ok(())
    }

    pub async fn register_parser(&self, language: String, parser: Box<dyn Parser>) -> Result<()> {
        let mut parsers = self.parsers.write().await;
        parsers.insert(language, parser);
        Ok(())
    }

    pub async fn get_parser(&self, _language: &str) -> Result<Option<Box<dyn Parser>>> {
        let _parsers = self.parsers.read().await;
        // Note: This is a simplified implementation
        // In practice, we'd need to clone or use Arc<dyn Parser>
        Ok(None)
    }
}

impl Default for IncrementalParseEngine {
    fn default() -> Self {
        Self::new()
    }
}

#[async_trait]
impl IncrementalEngine for IncrementalParseEngine {
    async fn update_graph(&self, change: &CodeChange) -> Result<GraphUpdateResult> {
        let start_time = std::time::Instant::now();
        let file_path = &change.file_path;

        info!("Starting incremental update for file: {}", file_path);

        // 1. Check cache for existing tree
        let content_hash = self.calculate_content_hash(&change.edit.new_text);
        let cache_key = format!("{}:{}", file_path, content_hash);

        let (old_tree, new_tree) = if let Some(cached_tree) = self.tree_cache.get(&cache_key) {
            debug!("Cache hit for file: {}", file_path);
            self.update_cache_metrics(true);

            // Use cached tree as new tree, get old tree from previous version
            let old_cache_key = format!("{}:prev", file_path);
            let old_tree = self.tree_cache.get(&old_cache_key).map(|entry| entry.tree.clone());
            (old_tree, Some(cached_tree.tree.clone()))
        } else {
            debug!("Cache miss for file: {}, parsing...", file_path);
            self.update_cache_metrics(false);

            // 2. Get appropriate parser
            let parsers = self.parsers.read().await;
            let parser = parsers
                .get(&change.language)
                .ok_or_else(|| {
                    crate::CodeGraphError::language_not_supported(
                        &change.language,
                        parsers.keys().cloned().collect(),
                    )
                })?;

            // 3. Get old tree from cache if available
            let old_cache_key = format!("{}:current", file_path);
            let old_tree = self.tree_cache.get(&old_cache_key).map(|entry| entry.tree.clone());

            // 4. Execute incremental parsing
            let parsed_tree = if let Some(ref old_tree_ref) = old_tree {
                // Incremental parsing with old tree
                parser.parse(&change.edit.new_text, Some(old_tree_ref.as_ref())).await?
            } else {
                // Full parsing for new file
                parser.parse(&change.edit.new_text, None).await?
            };

            // Convert Box to Arc for consistent type handling
            let new_tree: Arc<dyn SyntaxTree> = Arc::from(parsed_tree);

            // 5. Cache the new tree
            self.cache_syntax_tree(file_path, &new_tree, &content_hash).await?;

            (old_tree, Some(new_tree))
        };

        // 6. Compute node differences efficiently
        let node_diff = if let (Some(old), Some(new)) = (&old_tree, &new_tree) {
            // Check diff cache first
            let diff_cache_key = format!("{}:{}:{}", file_path,
                self.get_tree_hash(old),
                self.get_tree_hash(new));

            if let Some(cached_diff) = self.diff_cache.get(&diff_cache_key) {
                debug!("Using cached node difference for {}", file_path);
                cached_diff.clone()
            } else {
                debug!("Computing node differences for {}", file_path);
                let diff = self.compute_node_differences(old.as_ref(), new.as_ref()).await?;

                // Cache the difference
                self.diff_cache.insert(diff_cache_key, diff.clone());
                diff
            }
        } else {
            // No old tree, treat all nodes as added
            if let Some(new) = &new_tree {
                let new_nodes = self.extract_nodes_from_tree(new.as_ref()).await?;
                NodeDifference {
                    added: new_nodes,
                    removed: vec![],
                    modified: vec![],
                }
            } else {
                NodeDifference {
                    added: vec![],
                    removed: vec![],
                    modified: vec![],
                }
            }
        };

        // 7. Update graph structure with optimizations
        let result = self.update_graph_structure_optimized(&node_diff, change).await?;

        // 8. Update performance metrics
        let duration = start_time.elapsed();
        self.update_performance_metrics(file_path, duration.as_millis() as u64, &node_diff).await;

        // 9. Cleanup if needed
        if self.should_cleanup_cache().await {
            self.cleanup_cache().await?;
        }

        info!("Incremental update completed for {} in {}ms", file_path, duration.as_millis());

        Ok(GraphUpdateResult {
            success: true,
            duration_ms: duration.as_millis() as u64,
            added_nodes: node_diff.added.clone(),
            removed_nodes: node_diff.removed.clone(),
            modified_nodes: node_diff.modified.clone(),
            ..result
        })
    }

    async fn compute_node_differences(
        &self,
        old_tree: &dyn SyntaxTree,
        new_tree: &dyn SyntaxTree,
    ) -> Result<NodeDifference> {
        // Extract nodes from both trees
        let old_nodes = self.extract_nodes_from_tree(old_tree).await?;
        let new_nodes = self.extract_nodes_from_tree(new_tree).await?;

        // Create maps for efficient lookup
        let old_node_map: HashMap<String, NodeId> = old_nodes
            .into_iter()
            .map(|id| (format!("node_{}", id), id))
            .collect();

        let new_node_map: HashMap<String, NodeId> = new_nodes
            .into_iter()
            .map(|id| (format!("node_{}", id), id))
            .collect();

        // Compute differences
        let mut added = Vec::new();
        let mut removed = Vec::new();
        let mut modified = Vec::new();

        // Find added nodes
        for (key, node_id) in &new_node_map {
            if !old_node_map.contains_key(key) {
                added.push(*node_id);
            }
        }

        // Find removed nodes
        for (key, node_id) in &old_node_map {
            if !new_node_map.contains_key(key) {
                removed.push(*node_id);
            }
        }

        // Find potentially modified nodes
        for (key, node_id) in &new_node_map {
            if let Some(old_node_id) = old_node_map.get(key) {
                if self.nodes_differ(*old_node_id, *node_id).await? {
                    modified.push(*node_id);
                }
            }
        }

        Ok(NodeDifference {
            added,
            removed,
            modified,
        })
    }

    async fn propagate_changes(&self, changes: &NodeDifference) -> Result<Vec<NodeId>> {
        let mut affected_nodes = std::collections::HashSet::new();

        // 1. Direct impact analysis
        for node_id in &changes.modified {
            affected_nodes.insert(*node_id);
            // Add direct neighbors (simplified)
            let neighbors = self.get_node_neighbors(*node_id).await?;
            for neighbor in neighbors {
                affected_nodes.insert(neighbor);
            }
        }

        // 2. Indirect impact analysis
        let indirectly_affected = self.compute_indirect_impact(&affected_nodes).await?;
        for node_id in indirectly_affected {
            affected_nodes.insert(node_id);
        }

        // 3. Global impact analysis
        if self.has_global_impact(changes).await? {
            let globally_affected = self.compute_global_impact(changes).await?;
            for node_id in globally_affected {
                affected_nodes.insert(node_id);
            }
        }

        Ok(affected_nodes.into_iter().collect())
    }
}

impl IncrementalParseEngine {
    /// Calculate content hash for caching
    fn calculate_content_hash(&self, content: &str) -> String {
        use std::collections::hash_map::DefaultHasher;
        use std::hash::{Hash, Hasher};

        let mut hasher = DefaultHasher::new();
        content.hash(&mut hasher);
        format!("{:x}", hasher.finish())
    }

    /// Update cache hit/miss metrics
    fn update_cache_metrics(&self, cache_hit: bool) {
        let metrics_key = "global".to_string();
        let mut metrics = self.metrics.entry(metrics_key).or_insert_with(PerformanceMetrics::default);

        if cache_hit {
            metrics.cache_hit_rate = (metrics.cache_hit_rate * metrics.total_updates as f64 + 1.0) / (metrics.total_updates + 1) as f64;
        } else {
            metrics.cache_hit_rate = (metrics.cache_hit_rate * metrics.total_updates as f64) / (metrics.total_updates + 1) as f64;
        }
    }

    /// Cache a syntax tree with metadata
    async fn cache_syntax_tree(&self, file_path: &str, tree: &Arc<dyn SyntaxTree>, content_hash: &str) -> Result<()> {
        let cached_tree = CachedSyntaxTree {
            tree: tree.clone(),
            content_hash: content_hash.to_string(),
            cached_at: std::time::SystemTime::now(),
            access_count: 1,
            size_bytes: self.estimate_tree_size(tree.as_ref()),
        };

        // Cache with content hash
        let cache_key = format!("{}:{}", file_path, content_hash);
        self.tree_cache.insert(cache_key, cached_tree.clone());

        // Also cache as current version
        let current_key = format!("{}:current", file_path);
        if let Some(old_entry) = self.tree_cache.get(&current_key) {
            // Move current to previous
            let prev_key = format!("{}:prev", file_path);
            self.tree_cache.insert(prev_key, old_entry.clone());
        }
        self.tree_cache.insert(current_key, cached_tree);

        Ok(())
    }

    /// Get hash of a syntax tree
    fn get_tree_hash(&self, tree: &Arc<dyn SyntaxTree>) -> String {
        // Simple hash based on tree structure
        // In a real implementation, this would be more sophisticated
        use std::collections::hash_map::DefaultHasher;
        use std::hash::{Hash, Hasher};

        let mut hasher = DefaultHasher::new();
        tree.source().hash(&mut hasher);
        format!("{:x}", hasher.finish())
    }

    /// Estimate the memory size of a syntax tree
    fn estimate_tree_size(&self, _tree: &dyn SyntaxTree) -> u64 {
        // Simple estimation - in practice this would be more accurate
        1024 // 1KB estimate per tree
    }

    /// Update performance metrics
    async fn update_performance_metrics(&self, file_path: &str, duration_ms: u64, node_diff: &NodeDifference) {
        let mut metrics = self.metrics.entry(file_path.to_string()).or_insert_with(PerformanceMetrics::default);

        metrics.total_updates += 1;
        metrics.avg_update_time_ms = (metrics.avg_update_time_ms * (metrics.total_updates - 1) as f64 + duration_ms as f64) / metrics.total_updates as f64;
        metrics.nodes_processed += (node_diff.added.len() + node_diff.removed.len() + node_diff.modified.len()) as u64;
        metrics.memory_usage_bytes = self.estimate_current_memory_usage();
    }

    /// Check if cache cleanup is needed
    async fn should_cleanup_cache(&self) -> bool {
        let current_memory = self.estimate_current_memory_usage();
        current_memory > self.config.memory_cleanup_threshold
    }

    /// Cleanup old cache entries with enhanced memory management
    pub async fn cleanup_cache(&self) -> Result<()> {
        let start_time = std::time::Instant::now();
        let initial_memory = self.estimate_current_memory_usage();

        info!("Starting incremental engine cache cleanup - current usage: {} bytes", initial_memory);

        let cutoff_time = std::time::SystemTime::now() - std::time::Duration::from_secs(self.config.max_cache_age_seconds);
        let mut total_removed = 0;

        // 1. Remove old tree cache entries
        let mut tree_removed = 0;
        self.tree_cache.retain(|_, cached_tree| {
            if cached_tree.cached_at < cutoff_time {
                tree_removed += 1;
                false
            } else {
                true
            }
        });
        total_removed += tree_removed;

        // 2. Aggressive diff cache cleanup based on memory pressure
        let diff_cache_size = self.diff_cache.len();
        let max_diff_cache_size = if self.config.enable_aggressive_caching { 2000 } else { 1000 };

        if diff_cache_size > max_diff_cache_size {
            let entries_to_remove = diff_cache_size - max_diff_cache_size;
            let mut diff_removed = 0;

            // Remove oldest entries first (simple LRU approximation)
            let mut keys_to_remove = Vec::new();
            for entry in self.diff_cache.iter().take(entries_to_remove) {
                keys_to_remove.push(entry.key().clone());
            }

            for key in keys_to_remove {
                if self.diff_cache.remove(&key).is_some() {
                    diff_removed += 1;
                }
            }
            total_removed += diff_removed;
        }

        // 3. Clean up metrics for files that no longer exist
        let mut metrics_removed = 0;
        self.metrics.retain(|file_path, _| {
            let path = std::path::Path::new(file_path);
            if !path.exists() {
                metrics_removed += 1;
                false
            } else {
                true
            }
        });
        total_removed += metrics_removed;

        let final_memory = self.estimate_current_memory_usage();
        let memory_saved = initial_memory.saturating_sub(final_memory);
        let cleanup_time = start_time.elapsed();

        info!("Incremental engine cache cleanup completed: removed {} entries, saved {} bytes in {}ms",
              total_removed, memory_saved, cleanup_time.as_millis());

        Ok(())
    }

    /// Get memory usage statistics for the incremental engine
    pub async fn get_cache_stats(&self) -> IncrementalCacheStats {
        IncrementalCacheStats {
            tree_cache_size: self.tree_cache.len(),
            diff_cache_size: self.diff_cache.len(),
            metrics_count: self.metrics.len(),
            estimated_memory_usage: self.estimate_current_memory_usage(),
            max_cache_size: self.config.max_cache_size_bytes,
        }
    }

    /// Configure aggressive memory management
    pub fn enable_aggressive_memory_management(&mut self, enable: bool) {
        self.config.enable_aggressive_caching = !enable; // Inverse logic for memory management
        if enable {
            self.config.max_cache_size_bytes = self.config.max_cache_size_bytes / 2; // Reduce cache size
            self.config.max_cache_age_seconds = self.config.max_cache_age_seconds / 2; // Reduce cache age
        }
        info!("Aggressive memory management: {}", if enable { "enabled" } else { "disabled" });
    }

    /// Estimate current memory usage
    fn estimate_current_memory_usage(&self) -> u64 {
        let tree_cache_size: u64 = self.tree_cache.iter().map(|entry| entry.size_bytes).sum();
        let diff_cache_size = self.diff_cache.len() as u64 * 512; // Estimate 512 bytes per diff
        tree_cache_size + diff_cache_size
    }

    /// Enhanced graph structure update with optimizations
    async fn update_graph_structure_optimized(&self, node_diff: &NodeDifference, _change: &CodeChange) -> Result<GraphUpdateResult> {
        let start_time = std::time::Instant::now();

        // Process changes based on size and configuration
        if self.config.enable_parallel_processing && (node_diff.added.len() + node_diff.modified.len() + node_diff.removed.len()) > 10 {
            // Use parallel processing for large updates
            let _operations_count = self.process_node_changes_parallel(node_diff).await?;
        } else {
            // Sequential processing for small updates
            let _operations_count = self.process_node_changes_sequential(node_diff).await?;
        }

        let duration = start_time.elapsed();

        Ok(GraphUpdateResult {
            success: true,
            duration_ms: duration.as_millis() as u64,
            added_nodes: node_diff.added.clone(),
            removed_nodes: node_diff.removed.clone(),
            modified_nodes: node_diff.modified.clone(),
            ..GraphUpdateResult::default()
        })
    }

    /// Process node changes in parallel
    async fn process_node_changes_parallel(&self, node_diff: &NodeDifference) -> Result<u32> {
        use futures::future::join_all;

        let semaphore = Arc::new(tokio::sync::Semaphore::new(self.config.max_concurrent_workers));
        let mut total_operations = 0;

        // Create a helper function to avoid type issues
        let process_node = |semaphore: Arc<tokio::sync::Semaphore>, _node_id: NodeId| async move {
            let _permit = semaphore.acquire().await.unwrap();
            // TODO: Implement actual node processing
            Ok::<u32, crate::CodeGraphError>(1)
        };

        // Process all node types
        let mut tasks = Vec::new();

        for node_id in &node_diff.added {
            tasks.push(process_node(semaphore.clone(), *node_id));
        }

        for node_id in &node_diff.modified {
            tasks.push(process_node(semaphore.clone(), *node_id));
        }

        for node_id in &node_diff.removed {
            tasks.push(process_node(semaphore.clone(), *node_id));
        }

        let results = join_all(tasks).await;
        for result in results {
            total_operations += result?;
        }

        Ok(total_operations)
    }

    /// Process node changes sequentially
    async fn process_node_changes_sequential(&self, node_diff: &NodeDifference) -> Result<u32> {
        let mut operations_count = 0;

        // Process added nodes
        for _node_id in &node_diff.added {
            // TODO: Implement actual node addition
            operations_count += 1;
        }

        // Process modified nodes
        for _node_id in &node_diff.modified {
            // TODO: Implement actual node modification
            operations_count += 1;
        }

        // Process removed nodes
        for _node_id in &node_diff.removed {
            // TODO: Implement actual node removal
            operations_count += 1;
        }

        Ok(operations_count)
    }
    async fn extract_nodes_from_tree(&self, tree: &dyn SyntaxTree) -> Result<Vec<NodeId>> {
        let mut node_ids = Vec::new();

        // Get the appropriate language adapter
        let adapters = self.adapters.read().await;
        if let Some(adapter) = adapters.get(tree.language()) {
            // Extract nodes using the language adapter
            let nodes = adapter.extract_nodes(tree).await?;

            // Store nodes and collect their IDs
            for node in nodes {
                node_ids.push(node.id());
                // TODO: Store node in graph storage
            }
        }

        Ok(node_ids)
    }

    async fn nodes_differ(&self, old_id: NodeId, new_id: NodeId) -> Result<bool> {
        // For now, we'll assume nodes with different IDs are different
        // In a real implementation, we would:
        // 1. Retrieve both nodes from storage
        // 2. Compare their content, location, and metadata
        // 3. Return true if they differ significantly

        if old_id == new_id {
            Ok(false) // Same ID, likely same node
        } else {
            // TODO: Implement deep comparison by retrieving nodes from storage
            // and comparing their properties
            Ok(true) // Different IDs, assume different for now
        }
    }

    async fn get_node_neighbors(&self, _node_id: NodeId) -> Result<Vec<NodeId>> {
        // TODO: Implement actual neighbor lookup
        Ok(Vec::new())
    }

    async fn compute_indirect_impact(
        &self,
        _affected_nodes: &std::collections::HashSet<NodeId>,
    ) -> Result<Vec<NodeId>> {
        // TODO: Implement indirect impact analysis
        Ok(Vec::new())
    }

    async fn has_global_impact(&self, _changes: &NodeDifference) -> Result<bool> {
        // TODO: Implement global impact detection
        Ok(false)
    }

    async fn compute_global_impact(&self, _changes: &NodeDifference) -> Result<Vec<NodeId>> {
        // TODO: Implement global impact computation
        Ok(Vec::new())
    }

    // ===== CONFLICT DETECTION AND RESOLUTION =====

    /// Detect conflicts between concurrent updates
    pub async fn detect_update_conflicts(&self, file_path: &str, new_version: u64) -> Result<Vec<UpdateConflict>> {
        let mut conflicts = Vec::new();

        // Check if file is currently being processed
        if let Some(cached_tree) = self.tree_cache.get(&format!("{}:current", file_path)) {
            // Check for version conflicts
            if let Some(metrics) = self.metrics.get(file_path) {
                if metrics.total_updates > new_version {
                    conflicts.push(UpdateConflict {
                        conflict_type: ConflictType::VersionMismatch,
                        file_path: file_path.to_string(),
                        expected_version: new_version,
                        actual_version: metrics.total_updates,
                        description: "File has been updated by another process".to_string(),
                        resolution_strategy: ResolutionStrategy::MergeChanges,
                    });
                }
            }

            // Check for concurrent processing
            let current_time = std::time::SystemTime::now();
            if let Ok(duration) = current_time.duration_since(cached_tree.cached_at) {
                if duration.as_secs() < 1 {
                    conflicts.push(UpdateConflict {
                        conflict_type: ConflictType::ConcurrentUpdate,
                        file_path: file_path.to_string(),
                        expected_version: new_version,
                        actual_version: 0,
                        description: "File is currently being processed by another update".to_string(),
                        resolution_strategy: ResolutionStrategy::WaitAndRetry,
                    });
                }
            }
        }

        Ok(conflicts)
    }

    /// Resolve update conflicts using appropriate strategies
    pub async fn resolve_conflicts(&self, conflicts: Vec<UpdateConflict>) -> Result<ConflictResolution> {
        let mut resolution = ConflictResolution {
            resolved_conflicts: Vec::new(),
            failed_conflicts: Vec::new(),
            resolution_time_ms: 0,
        };

        let start_time = std::time::Instant::now();

        for conflict in conflicts {
            match conflict.resolution_strategy {
                ResolutionStrategy::WaitAndRetry => {
                    // Wait for a short period and retry
                    tokio::time::sleep(std::time::Duration::from_millis(100)).await;
                    resolution.resolved_conflicts.push(ResolvedConflict {
                        original_conflict: conflict,
                        resolution_method: "waited_and_retried".to_string(),
                        success: true,
                    });
                }
                ResolutionStrategy::MergeChanges => {
                    // Attempt to merge changes
                    let merge_result = self.attempt_merge_changes(&conflict).await;
                    resolution.resolved_conflicts.push(ResolvedConflict {
                        original_conflict: conflict,
                        resolution_method: "merged_changes".to_string(),
                        success: merge_result.is_ok(),
                    });
                }
                ResolutionStrategy::OverwriteOld => {
                    // Overwrite with new changes
                    resolution.resolved_conflicts.push(ResolvedConflict {
                        original_conflict: conflict,
                        resolution_method: "overwrite_old".to_string(),
                        success: true,
                    });
                }
                ResolutionStrategy::RejectNew => {
                    // Reject the new changes
                    resolution.failed_conflicts.push(conflict);
                }
            }
        }

        resolution.resolution_time_ms = start_time.elapsed().as_millis() as u64;
        Ok(resolution)
    }

    /// Attempt to merge conflicting changes
    async fn attempt_merge_changes(&self, conflict: &UpdateConflict) -> Result<()> {
        // This is a simplified merge strategy
        // In a real implementation, this would involve sophisticated merge algorithms
        info!("Attempting to merge changes for file: {}", conflict.file_path);

        // For now, we'll just log the attempt and return success
        // TODO: Implement actual merge logic based on AST differences
        Ok(())
    }

    /// Check if a file update can proceed without conflicts
    pub async fn can_update_safely(&self, file_path: &str, version: u64) -> Result<bool> {
        let conflicts = self.detect_update_conflicts(file_path, version).await?;

        // Check if all conflicts can be resolved automatically
        for conflict in &conflicts {
            match conflict.conflict_type {
                ConflictType::VersionMismatch => {
                    // Version mismatches can usually be resolved
                    continue;
                }
                ConflictType::ConcurrentUpdate => {
                    // Concurrent updates might need manual intervention
                    if conflict.resolution_strategy == ResolutionStrategy::RejectNew {
                        return Ok(false);
                    }
                }
                ConflictType::DataCorruption => {
                    // Data corruption always requires manual intervention
                    return Ok(false);
                }
            }
        }

        Ok(true)
    }

    async fn update_graph_structure(
        &self,
        _node_diff: &NodeDifference,
    ) -> Result<GraphUpdateResult> {
        // TODO: Implement actual graph structure updates
        Ok(GraphUpdateResult::default())
    }
}

/// Change detection component
pub struct ChangeDetector {
    // TODO: Add change detection state
}

impl ChangeDetector {
    pub fn new() -> Self {
        Self {}
    }

    pub async fn detect_changes(&self, change: &CodeChange) -> Result<AffectedRange> {
        // Analyze the text edit to determine the affected range
        let start_line = change.edit.start_position.row;
        let end_line = change.edit.new_end_position.row;

        // Expand the range to include potentially affected surrounding code
        let expanded_start = start_line.saturating_sub(5); // Look 5 lines before
        let expanded_end = end_line + 5; // Look 5 lines after

        Ok(AffectedRange {
            start_line: expanded_start,
            end_line: expanded_end,
            start_byte: change.edit.start_byte,
            end_byte: change.edit.new_end_byte,
        })
    }
}

impl Default for ChangeDetector {
    fn default() -> Self {
        Self::new()
    }
}

/// Represents the range of code affected by a change
#[derive(Debug, Clone)]
pub struct AffectedRange {
    pub start_line: u32,
    pub end_line: u32,
    pub start_byte: u32,
    pub end_byte: u32,
}

/// Change propagation engine
pub struct ChangePropagationEngine {
    // TODO: Add propagation state
}

impl ChangePropagationEngine {
    pub fn new() -> Self {
        Self {}
    }

    pub async fn propagate_changes(&self, changes: &NodeDifference) -> Result<PropagationResult> {
        let start_time = std::time::Instant::now();
        let mut affected_nodes = std::collections::HashSet::new();
        let mut propagation_depth = 0;

        // Start with directly changed nodes
        for node_id in &changes.added {
            affected_nodes.insert(*node_id);
        }
        for node_id in &changes.modified {
            affected_nodes.insert(*node_id);
        }
        for node_id in &changes.removed {
            affected_nodes.insert(*node_id);
        }

        // Propagate changes through dependencies
        let mut current_level = affected_nodes.clone();
        let max_depth = 5; // Prevent infinite propagation

        while !current_level.is_empty() && propagation_depth < max_depth {
            let next_level = std::collections::HashSet::new();

            for _node_id in &current_level {
                // TODO: Find nodes that depend on this node
                // For now, we'll just simulate some propagation
            }

            affected_nodes.extend(&next_level);
            current_level = next_level;
            propagation_depth += 1;
        }

        let processing_time = start_time.elapsed().as_millis() as u64;

        Ok(PropagationResult {
            affected_nodes: affected_nodes.into_iter().collect(),
            propagation_depth,
            estimated_update_time: processing_time,
        })
    }
}

impl Default for ChangePropagationEngine {
    fn default() -> Self {
        Self::new()
    }
}

/// Result of change propagation analysis
#[derive(Debug, Clone)]
pub struct PropagationResult {
    pub affected_nodes: Vec<NodeId>,
    pub propagation_depth: u32,
    pub estimated_update_time: u64,
}

/// Represents a conflict between concurrent updates
#[derive(Debug, Clone)]
pub struct UpdateConflict {
    pub conflict_type: ConflictType,
    pub file_path: String,
    pub expected_version: u64,
    pub actual_version: u64,
    pub description: String,
    pub resolution_strategy: ResolutionStrategy,
}

/// Types of update conflicts
#[derive(Debug, Clone, PartialEq)]
pub enum ConflictType {
    /// Version mismatch between expected and actual
    VersionMismatch,
    /// Concurrent update in progress
    ConcurrentUpdate,
    /// Data corruption detected
    DataCorruption,
}

/// Strategies for resolving conflicts
#[derive(Debug, Clone, PartialEq)]
pub enum ResolutionStrategy {
    /// Wait for current operation to complete and retry
    WaitAndRetry,
    /// Attempt to merge changes intelligently
    MergeChanges,
    /// Overwrite old changes with new ones
    OverwriteOld,
    /// Reject new changes and keep old ones
    RejectNew,
}

/// Result of conflict resolution
#[derive(Debug)]
pub struct ConflictResolution {
    pub resolved_conflicts: Vec<ResolvedConflict>,
    pub failed_conflicts: Vec<UpdateConflict>,
    pub resolution_time_ms: u64,
}

/// A successfully resolved conflict
#[derive(Debug)]
pub struct ResolvedConflict {
    pub original_conflict: UpdateConflict,
    pub resolution_method: String,
    pub success: bool,
}

/// Cache statistics for the incremental engine
#[derive(Debug, Clone)]
pub struct IncrementalCacheStats {
    pub tree_cache_size: usize,
    pub diff_cache_size: usize,
    pub metrics_count: usize,
    pub estimated_memory_usage: u64,
    pub max_cache_size: u64,
}
